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Mammalian pregnancy is a curious life phenomenon. Immunologically, the mechanism of pregnancy is difficult to explain because it involves the coexistence of an external foreign body (the embryo) and the host (the mother) for a period of time. How did mammals acquire the ability to become pregnant in parallel with altered immunity? Sex in the evolution of life and its impact on anthropology are major topics of discussion. In this paper, we outline (1) sex and evolution in mammals after the advent of our direct ancestors (apes) up to humans (i.e., the Cenozoic Quaternary), including anthropological aspects such as the development of the central nervous system; (2) the development of reproductive immunity during the Paleozoic era, when biodiversity developed explosively (and many sexually reproducing organisms have emerged); and (3) the characteristic reproductive strategies of mammals, including humans with the immunological aspects of viviparity. We present an overview of mammalian reproductive immunity, which is a heretical aspect of immunology.

Infections with parasites, especially those involving nematodes that invade tissues, induce a strong Th2-type immune response, which increases immunoglobulin E and eosinophil levels in the blood and tissues. Eosinophils are not effective against all possible helminth infections, but are known to be effective against nematode larvae. In particular, when a host is re-infected by a species of nematode that it previously encountered, the activation of acquired immunity causes robust accumulation and activation of eosinophils that damages the nematode larvae. Eosinophil production and activation processes are mainly induced by interleukin (IL)-5, which is produced by Th2 cells and group 2 innate lymphoid cells, and eosinophils have been shown to generally participate in host defense, inflammation, and immunomodulation. Recently, several papers have reported host defense by non-antigen-specific immune activation, in which group 2 innate lymphoid cells and Th2 cells produce interleukin (IL)-5 and IL-13 in response to IL-33 stimulation. This immune activation is produced by migrating larvae of a species that differs from the species previously encountered. Eosinophils also play an important role in the eradication of migrating larvae. Thus, eosinophils contribute to host defense in both antigen-specific and non-antigen-specific manners.

Atopic dermatitis (AD) is the most common inflammatory skin disease driven by both terminal keratinocyte differentiation defects and type 2 immune responses, and this condition causes psychological and social morbidity. Although patients with severe AD require systemic immunotherapy, conventional agents including ciclosporin could not be used for several years due to side effects such as nephrotoxicity, hypertension and long-term risks of malignancy. It is well known that dupilumab, which blocks receptor binding of both IL-4 and IL-13, is remarkably efficacious in the treatment of AD. We have entered a new era when many novel topical and systemic agents that may have great potential in AD treatment are emerging through clinical trials. The purpose of this article is to summarize the efficacy and safety of the current topical and systemic therapies in AD by reviewing recently published papers regarding phase II/III clinical trials. It is revealed that topical phosphodiesterase 4 inhibitors and Janus kinase (JAK) inhibitors are promising treatments for AD. Moreover, systemic therapies such as biologics targeting IL-13 and oral JAK inhibitors show strong efficacy in AD.